Vertical Models
7
Symptom
Possible Cause(s)
Corrective Action
Excessive noise
(knocking)
Continued
Large quanity of oil in the
discharge air
NOTE:
In an oil
lubricated compressor there
will always be a small
amount of oil in the air
stream.
Water in discharge air/tank
Motor hums and runs
slowly or not at all
Reset mechanism cuts out
repeatedly or fuses blow
repeatedly
Tank does not hold
pressure when compressors
off and the shut off valve is
closed
Pressure switch
continuously blows air out
the unloader valve
Pressure switch does not
release air when the unit
shuts off
Excessive vibration
6. Noisy check valve in
compressor system
1. Worn piston rings
2. Compressor air intake
restricted
3. Excessive oil in
compressor
4. Wrong oil viscosity
1. Normal operation. The
amount of water
increases with humid
weather
1. Use of extension cord
2. Malfunctioning check
valve or unloader valve
3. Low voltage
4. Malfunctioning pressure
switch - contacts will not
close
1. Too many devices on
same circuit
2. Incorrect fuse size or
circuit breaker
3. Malfunctioning check
valve
4. Pressure switch set too
high
5. Loose wiring
6. Malfunctioning motor
1. Worn check valve
2. Check all connections
and fittings for leaks
3. Check tank for cracks or
pin holes
1. Malfunctioning check
valve
1. Malfunctioning unloader
valve on pressure switch
1. Loose fasteners
2. Belt needs replaced
3. Belt alignment
6. Replace.
Do not disassemble check valve with
air pressure in tank
1. Replace with new rings. Maintain oil level and change oil
more frequently.
2. Clean filter. Check for other restrictions in the intake
system.
3. Drain down to full level.
4. Use Mobil 1
®
10W-30
1. Drain tank more often. At least daily.
2. Add a filter to reduce the amount of water in the air line.
1. Do not use an extension cord. Use longer air hose with
larger diameter.
2. Replace check valve, unloader valve or pressure switch.
Do not disassemble check valve with
air pressure in tank
3. Check with voltmeter, check reset switch on motor. If reset
switch trips repeatedly, find and correct the cause. See next
item.
4. Repair or replace pressure switch.
1. Limit the circuit to the use of only the air compressor.
2. Be sure that fuses or circuit breakers are rated properly.
3. Replace check valve.
Do not disassemble check valve with
air pressure in tank
4. Adjust or replace.
5. Check all electrical connections.
6. Replace motor.
1. Replace check valve.
Do not disassemble check valve with
air pressure in tank
2. Tighten.
3. Replace tank. Never repair a damaged tank.
1. Replace the check valve if the unloader valve bleeds off
constantly.
Do not disassemble check valve with
air pressure in tank
1. Replace the pressure switch if it does not release the
pressure for a short period of time when the unit shuts off.
Do not disassemble pressure switch with
air pressure in tank
1. Tighten.
2. Replace with correct size.
3. Align flywhell and pulley.
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Troubleshooting Chart (Continued)
